I didn't have time to add an explanation to my earlier post with the pulleys, so here it is:
I would wrap some protective tape around the keel aft of the rear wire attachment point. Then I would use a simple hose clamp to clamp a light cord to the keel (with appropriate protection for the cord). I would tie a small pulley (like one of the one's listed earlier) to the haul-back line. Pass the rope from the hose clamp through the pulley and back toward the rear of the keel. This will give you a 2 to 1 advantage when hauling back. But more importantly, it will let you tension it to some degree and then tie it off so the sail can "relax" at that new tension. Then after a few hours, add some more tension and tie it off again. Here's a sketch of what that might look like:
- Single_Pulley_HaulBack_640.png (59.41 KiB) Viewed 1236 times
This drawing doesn't show it, but you might want to tie the loose end (aft of the hose clamp) back to the line running from the clamp to the pulley so it doesn't get away if it slips through the hose clamp. You might also add a small loop at that point to tie off the free end of the tensioning cord.
Now you could add more pulleys to gain greater mechanical advantage (3 to 1, 4 to 1, ...), but I think the 2 to 1 sketched here should be sufficient for a sail that's just a bit too tight. More importantly, the 2 to 1 advantage is less likely to break anything!
And speaking of breaking things, this setup gives you the ability to tie off the tension so you can inspect for where anything might be binding. I would do that initially with practically no tension. When you're sure that nothing else is binding (misrouted wires for example), then you can begin to slowly increase the tension as I've mentioned above.
Be sure that you do this in a safe place where the glider is properly tied down so it doesn't get away and damage itself or anything else.
Also, to address Joe's points, I've had haulback challenges with a number of gliders (including my own Falcon). It seems to be most pronounced when the glider hasn't been flown for a long time. It may be worsened by cycling of temperature and moisture in storage. I've also seen some of the early Falcons develop a pretty severe "puckering" along the leading edge between the battens on some older beach gliders. I suspect that these changes do affect flight characteristics to some degree, but they still seemed to fly pretty well (at least at the beach).
Regarding compression of the keel, that might be an issue, but I suspect that the potential flight loads on the haulback system are quite a bit greater than what comes from tensioning in normal circumstances. So the keel should be designed for more than that amount of compression stress.
Regarding the haulback cleat, that's exactly what we did with
Little Hawk. But Little Hawk uses a rope for a haulback and not a steel cable. I don't think a rope in a cleat would pass HGMA standards. Now what I have seen (and you may remember this), is that some of the Condor's at Windsports have an extra "tang" bolted to the original haulback tang. I'm not sure if that's standard from the factory or an improvised modification. But it does add about an extra inch to the haulback line. So that's always an option.
By the way Joe, while I was looking for that Little Hawk link, I found this photo:
- CutCrossBar.JPG (28.56 KiB) Viewed 1234 times
Please notice what I'm holding in my right hand.
Home
